KGO-TV reports that 59-year-old Debbie Gratz is scheduled to appear in court again later this month.
She was arrested Friday after a colleague at the Morgan Hill Kiddie Academy saw her put an unknown substance into the children's cups.
School officials notified police on Monday, who said Gratz acknowledged putting the over-the-counter sleeping aid "Sominex" into the kids' drinks.
None of the children drank from the cups the day the incident was reported.
Gratz did not return calls to KGO seeking comment.
